High speed rotor used for centrifugal separation



April 26, 1966 J. P. FELTMAN, JR., ETAL 3,243,046

HIGH SPEED ROTOR USED FOR CENTRIFUGAL SEPARATION Filed July 2, 1965 H l I INVENTORS H Jam r2 FELT/7AM JR.

BY WiLL/ANLLP/E/YU/VTE United States Patent l 3,248,046 HIGH SPEED ROTOR USED FOR CENTRIFUGAL Y SEPARATION John P. Feltman, JL, 1 74th St., Brooklyn, N.Y., and William J. Piemonte, 2135 80th St., Brooklyn, N.Y. Filed July 2, 1965, Ser. No. 469,242 2 Claims. (Cl. 233-26) This is a continuation-in-part of application Ser. No. 361,967, filed April 23, 1964, and now abandoned.

This invention relates to high speed rotors used in centrifuges and more specifically in the construction of a rotor built up of superposed layers of glass fibers that are bonded together to form a balanced solid rotor provided with small tube holding apertures or bores.

Rotors of aluminum, heat treated steel and titanium are well known in the-art. However, all of these rotors are limited to a degree of centrifugal force at which they break down and will disintegrate, for example, the tensile strength of the materials.

Aluminum will not exceed 85,000 lbs. per square inch.

Titanium will not exceed 170,000 lbs. per square inch.

Heat treated steel will not exceed 250,000 lbs. per square inch.

The density of the materials must be considered:

Aluminum .097 Titanium .165 Heat treated steel .285

Thus the strength to Weight ratio is approximately 880,000 lbs. per square inch.

It is also to be noted that spinning buckets are well known in the art. In spinning buckets for rayon or artificial silk, the bucket is formed as a bowl with a central open chamber. These buckets are designed for normal operating speeds of 9000 r.p.m. and according to Patent No. 2,965,220 they will, under test, rupture at 14,900 r.p.m. It is also to be noted that in all of the prior art relating to spinning buckets, the bucket or rotor is constructed as a cylindrical wall extendingfrom a supporting base in which the walls of the bowl are comparatively light or thin and in which the wall may be composed of a fibrous strip with a binder as in Patent No. 2,028,040, or a cellulosic fabric material impregnated and bonded together with a phenolic resin as in Patent No. 2,965,220, or as a fibrous material impregnated with resinoid and reinforced with a circumferentially placed wrapping of stainless steel wire as in Patent No. 2,436,716, or of glass yarn as disclosed in Patent No. 2,594,693, or as a molded bucket having fiber glass in the wall on a reinforcing medium.as disclosed in Patent- No. 2,525,469, or the combination of a glass fiber warp with a cotton fill in a molded bucket of artificial resins as disclosed in Patent No. 2,372,983, or the use of a glass fiber thread or strand as reinforcement in a molded resinous roller as in the Dutch Patent No. 87,740, or the molding of a plurality of layers of a mixture of an organic fibrous material and an acid resistant asbestos woven into a fabric as in Patent No. 2,128,097, but in all the art on spinning buckets the speeds or r.p.m. indicated is a modest 1415,000 r.p.m.

It is also to be noted that pipe is constructed by wrapping glass fibers about a mandrel and impregnating the glass fibers with a thermo setting plastic binder. In all pipe formed by this method there is a comparatively thin pipe wall formed that is exceedingly strong, but never subject to centrifugal forces.

In the presently known rotors the centrifuge that may be constructed of aluminum, titanium or heat treated steel the strength to weight ratio is low, that is while aluminum is light it has a low tensile strength and .')',Z48,046 Patented Apr. 26, 1966 where heat treated steel has a high tensile strength it is heavy. The presently known rotors using metal are operating up to 60,000 r.p.m. In one example of their use that is in the separation of viruses, the rotors operating at 60,000 r.p.m. take from 60 to 70 hours for actual separation of the virus. In the present invention the rotors will operate at 100,000 r.p.m. and the same separation of viruses will be performed in from 2 to 3 hours.

In the present invention the article or rotor is formed as a solid body as in all rotors designed for holding tubes or bottles for centrifugal separation processes. Also in the present invention the rotor must be capable of extremely high r.p.m. to produce a centrifugal force over 250,000 X gravity and up to 325,000 gs, for the separation of certain viruses in a reasonably minimum time in clinical study.

It is an object of the invention to provide a high speed rotor for holding tubes or bottles for'centrifugal separation of substances requiring a force of over 250,000 X gravity.

It is a further object of this invention to provide a high speed rotor for holding tubes or bottles in a centrifuge in which the rotor is constructed solely of glass fiber filament wound in superposed layers and impregnated with a thermosetting binder to form a solid body that is capable of withstanding a centrifugal force in excess of 250,000 'X gravity.

Other objects of this invention will be apparent by reference to the detailed description and the drawings in which FIG. 1 is a plan view of a rotor.

FIG. 2 is a side view partially in cross section, and

FIG. 3 is an elevational view illustrating the method of forming the rotor.

Referring to the drawings there is illustrated a rotor member R, FIGS. 1 and 2 which is constructed as illustrated in FIG. 3 by winding upon a mandrel 24 a narrow strip or strand of glass fiber material 10 while a plastic material such as resin is sprayed by gravity upon each convolution of the glass fiber material simultaneously with the winding of the glass fiber material. The glass fiber strand is fed through a guiding member 66 passing through a hub member 12 which is slotted lengthwise so as to exert friction upon the glass fiber thread to cause the thread to Wind over the mandrel 24 with a uniform predetermined tension. The rotation of the mandrel 24 and the simultaneous back and forth operation of the glass fiber thread 10 by means of the movement of the guiding member 66 back and forth produces a uniform coiling of the strand 10 over mandrel 24 and continues to superpose layers of strand one-upon the other to build up the rotor body R. One end of mandrel 24 as shown in FIG. 3 is supported by the point 18 fitted in the tail stock spindle of a winding machine while the opposite end of mandrel 24 is supported by the head stock of the winding machine. The head stock receiving the reduced end 15 of mandrel 24. Positioned between disc 13 and the superposed layers of strand 10 is a second disc 16 having a pin 17 extending laterally therefrom for engaging an opening in disc 13 thus keying the disc member 16 to disc 13 of the head stock. To assist in forming the rotor. R there is provided a cylindrically shaped member 19 mounted on the tail stock for rotary movement only. A hub 20 is mounted on the cylindrically shaped member 19 for sliding movement. Member 20 is formed with a disc portion 21, the disc portion having a diameter corresponding to the larger coiled diameter of the rotor to be formed, the cylindrical member 19 and the disc 21 serving to hold the glass fiber strand 10 in a plane at right angles to the axis of the mandrel during the coiling of the glass fiber thread. The sliding movement of disc 21 on the cylindrically shaped member 19 is affected manually and is set by a pin 23 engaging a groove 50 as shown in FIG. 3. Thus the disc may be set in the dotted position for winding and forming rotor R as illustrated. A sleeve 26 may be placed over the mandrel 24 to prevent the adherence of the plastic material to the mandrel and thus permit removal of the rotor after the cooling of the plastic material. Likewise a disc .25 of an appropriate material may be placed against the face of disc 21 and another disc 25 may be placed against the face of disc 16. Thus the strand 10 will not adhere to either disc or to the mandrel and the rotor R may be easily removed. To start the winding of the strand 10 upon mandrel 24', one

end of strand is hooked to the discs 13 and 16 and coiled over the sleeve 26 at a pitch corresponding to the size of the fiber glass thread used and the winding is continued with the strand 10 being fed through hub member 12 and by movement of guide member 66, the actual'desired contour of rotor R may be formed as shown in FIG. 3. The rotor R is removed from mandrel 24 and then cured forming an integral body from the wound strand 10. The rotor R may then be treated as a solid body for machining its outer periphery to provide a perfect balance or any variation in shape as desired. It may also be drilled to provide a plurality of cylindrical bores L1, L2, L3, L4, L5, etc., of a size to permit the insertion of laboratory tubes as illustrated in FIG. 2 thus completing the rotor R for use in a centrifuge. The glass fiber material or strand 10 approximates .075 lb. per cubic inch. The tensile strength of this strand is approximately 200,000 plus lbs. per square inch. Thus the strength to weight ratio equals 4.75 which is a strength to weight ratio of 2,700,- 000 inches approximately. Thus the tensile strength of the rotor R, because of the relatively low density and high strength of the glass fiber as bonded together, possesses a weight to strength ratio of approximately 240% above that of any other material heretofore used for rotors and due to its build up of superposed layers into a solid or integrally formed rotor, the rotor R does trifugal separation of materials, it is to be understood that the bores may be varied in their shape to retain any desired type of tube or bottle and the number of bores may be varied according to the particular type of rotor utilized and the size of the rotor may be varied, that is, a small rotor will be utilized for the extremely high rpm. while a larger rotor may be utilized for a lesser rpm. and desired centrifugal force for separation.

strength strand, namely, glass fiber bonded together to provide the strongest possible rotor for extremely. high r.p.m. operation'and extremely high centrifugal force for separation :as a centrifuge. Changes in the glass fiber as to its contour whether round, square, etc., may be made as long as the fiber retains its lightweight and high tensile strength. without departing from the spirit of this inlationship, said bores extending radially into said rotor so that the base of the bores are positioned in a greater;

diametrical relation than the upper portion of said bores.

2. A solid rotor for a centrifuge which may be sub-.

jected to a stress of'250,000 X gravity during its oper ation, comprising a generally cylindrical form having its 1 lower portion with a greater diameter than -its upper. portion and formed of superposed layers of binder treated glass fiber with the turns of one layer being overlapped by the turns of the next layer whereby the glass fiber filaments of all layers are interlocked into an internal balanced rotor having uniform density, the external layers of said rotor provided with atv least two small bottle holding bores that are radially spaced in equal and dynamically balanced relationship, said bores extending radially into said rotor.

References Cited by the Examiner UNITED STATES PATENTS 2,028,040 1/1936 Benge 57--76 2,128,097 8/1938 Mains 5776 X 2,372,983 4/ 1945 Richardson 5776 2,436,726 2/ 1948 Moyer 57-76 2,525,469 10/195'0 Anderson 57-76 2,594,693 4/ 1952 Smith 5776 X 2,965,220 12/1960 Naul 5776X FOREIGN PATENTS 87,740 3/ 1958 Netherlands.

M. CARY NELSON, Primary Examiner;

It is also to be understood that the rotor R is solely constructed of the lightest weight toughest tensile 1 

1. A CENTRIFUGAL ROTOR COMPRISING A SOLID CORE WITH A BASE, SAID CORE COMPRISING A PLURALITY OF INTERNAL AND EXTERNAL LAYERS OF GLASS FIBER IMPREGNATED WITH A RESINOUS BINDER, THE EXTERNAL LAYERS OF SAID CORE BEING PROVIDED WITH AT LEAST TWO SMALL BOTTLE HOLDING BORES THAT ARE RADIALLY SPACED IN EQUAL AND DYNAMICALLY BALANCED RELATIONSHIP, SAID BORES EXTENDING RADIALLY INTO SAID ROTOR SO THAT THE BASE OF THE BORES ARE POSITIONED IN A GREATER DIAMETRICAL RELATION THAN THE UPPER PORTION OF SAID BORES. 